Pharmacokinetics of trimethoprim-sulphamethoxazole in two-day-old foals after a single intravenous injection.
Six healthy two-day-old foals (3 pony foals and 3 horse foals) were given a single intravenous (iv) injection of trimethoprim (TMP)--sulphamethoxazole (SMZ) at a dosage of 2.5 mg of TMP/kg bodyweight (bwt) and 12.5 mg of SMZ/kg bwt. Serum TMP and SMZ concentrations were measured serially during a 24 hour period. The overall elimination rate constant (K) for TMP in the pony and horse foals was 0.45/h, whereas the K values for SMZ for the pony and horse foals were 0.12/h and 0.07/h, respectively (no significant difference; P greater than 0.05). Based on published minimum inhibitory concentration values for equine pathogens (Adamson et al 1985), the primary indication for the use of TMP/SMZ in foals may be in the treatment of infections caused by gram-positive bacteria. A dosage of 2.5 mg of TMP/kg bwt and 12.5 mg of SMZ/kg bwt, given iv at 12 h intervals would be appropriate.
Brown
M P
MP
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610-0136.
McCartney
J H
JH
Gronwall
R
R
Houston
A E
AE
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D006736:Horses / Q000378:metabolism*; D007275:Injections, Intravenous / Q000662:veterinary; D013420:Sulfamethoxazole / Q000097:blood; D014295:Trimethoprim / Q000097:blood; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000008:administration & dosage / Q000493:pharmacokinetics*
D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D014295:Trimethoprim; D013420:Sulfamethoxazole